This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Recent studies on stem-like cancer cells (SLCC) suggest a potential reason for the low efficacy of current cancer therapies and a way to improve them. Current cancer chemo- and radio-therapies target the rapidly-dividing cells in a tumor, however a tumor is a heterogeneous population of cells. Comprising a small amount of the population, SLCC remain relatively static and initiate the proliferative cells that account for the majority of the tumor mass. These SLCC are essentially dormant and resistant to chemo- and radio-therapy. SLCC remain after therapy and retain their ability to initiate proliferative cancer cells;therefore, it is believed SLCC are the source of metastasis and relapse. However, there is controversy over the definition of SLCC and their role in cancer development and progression. Using bladder cancer as a model, we aim to show SLCC in bladder cancer tumors are much older than the bulk of the tumor, resistant to conventional chemo- and radio-therapy and responsible for metastasis and relapse. The first part of the project involves isolating stem cell populations from three bladder cancer cell lines with a range of responses to the chemotherapeutic agent, cisplatin. The cycling of these cells will be examined in addition to their ability to demonstrate properties associated with stem cells as demonstrated through colony-forming assays, long term proliferation, differentiation and response to chemotherapy and radiation. Initially we plan to isolate CD44+,CD66C- as our stem cell population, as this has the strongest support in the literature. A side-scatter population has also been reported to possess stem cell capabilities in several bladder cancer lines and may also be investigated. The second goal of the project is to investigate SLCC in fresh human bladder tumor samples. The age of SLCC isolated from fresh tumor samples along with non-stem cells will be determined using the 14C bomb curve with AMS. The elevation of 14C/C in the DNA of these sorted cells will be used to assign a date of synthesis. This date of synthesis can be compared to the medical history of the patient in order to determine where on the timeline of tumor development SLCC fall. Finally, we will develop a new tool for use in cancer research by producing SLCC with highly labeled DNA. Labeled cancer stem cells will be produced from one of the lines used in the initial part of the project based upon the percentage of stem cells and cell cycle properties. These labeled SLCC can then be used in research on their metastatic potential and as a tracer in cancer research. AMS will allow us to follow individual cells. This work has the power to transform the current methods used to treat cancer. Existing therapies are developed primarily against the highly proliferative cells that make up the bulk of the tumor. By definitively measuring the longevity of SLCC, they can be confirmed as the reason for relapse and metastasis. The creation of labeled SLCC will provide a new tool to be used in cancer research and change the direction of the field.